Nuclear Theory·nucl-th

Monday·October 17, 2022

12 papers—5 primary·7 cross-listed

01
[Submitted on 13 Oct 2022]
Optical potentials for the rare-isotope beam era
C. Hebborn🇺🇸 · F. M. Nunes🇺🇸 · G. Potel🇺🇸 · W. H. Dickhoff🇺🇸 · J. W. Holt🇺🇸 · M. C. Atkinson🇺🇸 · R. B. Baker🇺🇸 · C. Barbieri🇮🇹 · G. Blanchon🇫🇷 · M. Burrows🇺🇸 · R. Capote🇦🇹 · P. Danielewicz🇺🇸 and 17 other authors
We review recent progress and motivate the need for further developments in nuclear optical potentials that are widely used in the theoretical analysis of nucleon elastic scattering and reaction cross sections. In regions of the nuclear chart away from stability, which represent a frontier in nuclear science over the coming decade and which will be probed at new rare-isotope beam facilities worldwide, there is a targeted need to quantify and reduce theoretical reaction model uncertainties, especially with respect to nuclear optical potentials. We first describe the primary physics motivations for an improved description of nuclear reactions involving short-lived isotopes, focusing on its benefits for fundamental science discoveries and applications to medicine, energy, and security. We then outline the various methods in use today to build optical potentials starting from phenomenological, microscopic, and ab initio methods, highlighting in particular the strengths and weaknesses of each approach. We then discuss publicly-available tools and resources facilitating the propagation of recent progresses in the field to practitioners. Finally, we provide a set of open challenges and recommendations for the field to advance the fundamental science goals of nuclear reaction studies in the rare-isotope beam era.
Comments:
This paper is the outcome of the Facility for Rare Isotope Beams Theory Alliance (FRIB - TA) topical program "Optical Potentials in Nuclear Physics" held in March 2022 at FRIB. Its content is non-exhaustive, was chosen by the participants and reflects their efforts related to optical potentials
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2210.07293 [pdf]
J.Phys.G(2023)·76 citations
02
[Submitted on 13 Oct 2022]
Light-nuclei production in heavy-ion collisions within a thermodynamical approach
M. Kozhevnikova🇷🇺 · Yu. B. Ivanov🇷🇺
We present results of simulations of light-nuclei production in relativistic heavy-ion collisions within updated Three-fluid Hydrodynamics-based Event Simulator Extended by UrQMD (Ultra-relativistic Quantum Molecular Dynamics) final State interactions (THESEUS). The simulations were performed for Pb+Pb and Au+Au collisions in the collision energy range of $s_{N N} =$ 6.4--19.6 GeV. The light-nuclei production is treated within the thermodynamical approach on equal basis with hadrons. The only additional parameter related to the light nuclei is the energy density of late freeze-out that imitates afterburner stage of the collision because the light nuclei do not participate in the UrQMD evolution. This parameter is fixed from the condition of the best reproduction of the proton transverse-momentum spectrum after the UrQMD afterburner by that at the late freeze-out. The updated THESEUS results in not perfect, but a reasonable reproduction of data on bulk observables of the light nuclei, especially their functional dependence on the collision energy and light-nucleus mass. Various ratios, $d / p$ , $t / p$ , $t / d$ , and $N (t) \times N (p) / N^{2} (d)$ , are also considered. The directed flow of light nuclei turns out to be more involved. Apparently, it requires explicit treatment of the afterburner evolution of light nuclei that violates the kinetic equilibrium. Imperfect reproduction of the light-nuclei data leaves room for medium effects in produced light nuclei.
Comments:
12 pages, 11 figures. Version published in PRC, discussion extended
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2210.07334 [pdf]
PRC(2023)·5 citations
03
[Submitted on 14 Oct 2022]
Spheroidal expansion and freeze-out geometry of heavy-ion collisions in the few-GeV energy regime
Szymon Harabasz🇩🇪 · Jędrzej Kołaś🇵🇱 · Radosław Ryblewski🇵🇱 · Wojciech Florkowski🇵🇱 · Tetyana Galatyuk🇩🇪 · Małgorzata Gumberidze🇩🇪 · Piotr Salabura🇵🇱 · Joachim Stroth🇩🇪 · Hanna Paulina Zbroszczyk🇵🇱
A spheroidal model of the expansion of hadronic matter produced in heavy-ion collisions in the few-GeV energy regime is proposed. It constitutes an extension of the spherically symmetric Siemens-Rasmussen blast-wave model used in our previous works. The spheroidal form of the expansion, combined with a single-freeze-out scenario, allows for a significantly improved description of both the transverse-mass and the rapidity distributions of the produced particles. With the model parameters determined by the hadronic abundances and spectra, we make further predictions of the pion HBT correlation radii that turn out to be in a qualitative agreement with the measured ones. The overall successful description of the data supports the concept of spheroidal symmetry of the produced hadronic systems in this energy range.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2210.07694 [pdf]
PRC(2023)·6 citations
04
[Submitted on 14 Oct 2022]
Resolving the $R_{pA}$ and $v_{2}$ puzzle of $D^{0}$ mesons in $p -$ Pb collisions at the LHC
Chao Zhang🇺🇸 · Liang Zheng🇨🇳 · Shusu Shi🇨🇳 · Zi-Wei Lin🇺🇸
It has been a challenge to understand the experimental data on both the nuclear modification factor and elliptic flow of $D^{0}$ mesons in $p -$ Pb collisions at LHC energies. In this work, we study these collisions with an improved multi-phase transport model. By including the Cronin effect (i.e., transverse momentum broadening) and independent fragmentation for charm quarks, we provide the first simultaneous description of the $D^{0}$ meson $R_{pA}$ and $v_{2}$ data at $p_{T} \leq 8$ GeV $/ c$ . The model also reasonably describes the $D^{0}$ meson $p_{T}$ spectra and the low- $p_{T}$ charged hadron spectra, $R_{pA}$ and $v_{2}$ . Our results show that both parton interactions and the Cronin effect are important for the $D^{0}$ meson $R_{pA}$ , while parton interactions are mostly responsible for the $D^{0}$ meson $v_{2}$ . It is thus essential to include the Cronin effect for the simultaneous description of the $D^{0}$ meson $R_{pA}$ and $v_{2}$ . This work implies that the Cronin effect could also be important for heavy hadrons in large systems.
Comments:
6 pages, 3 figures, the Cronin strength is reduced, comparisons with the HVQMNR code are corrected
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2210.07767 [pdf]
PLB(2023)·24 citations
05
[Submitted on 14 Oct 2022]
Scales in light-nuclei production near the QCD critical point
Shanjin Wu🇨🇳 · Koichi Murase🇯🇵 · Huichao Song🇨🇳
Based on the coalescence model, we analyse the light-nuclei production near the critical point by expanding the phase-space distribution function $f (r, p)$ in terms of the phase-space cumulants $\sim ⟨ r^{m} p^{m} ⟩_{c}$ . We show that the dominant contribution of the phase-space distribution to the yield of light nuclei is determined by the second-order phase-space cumulants. Here, we identify the fireball size, the homogeneity length, and the effective temperature, which are encoded in the second-order phase-space cumulants, as the relevant scales in explaining the yield of light nuclei. These scales are typically much larger than the correlation length of the critical fluctuations created in the rapid expansion of the heavy-ion systems, so we need to eliminate this dominant contribution of the relevant scales in order to isolate the critical contribution from the yield of light nuclei. We find that the second-order phase-space cumulants appeared in the yields of light-nuclei with different mass numbers share a similar structure. This property allows us to construct ratios of light-nuclei yields in appropriate combinations so that the effect of the relevant scales of the light-nuclei yield cancels, which isolates the critical effects.
Comments:
5 pages. Contribution to The Tenth Annual Conference on Large Hadron Collider Physics (LHCP2022)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2210.07841 [pdf]
PoS(2023)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Optical potentials for the rare-isotope beam era

Light-nuclei production in heavy-ion collisions within a thermodynamical approach

Spheroidal expansion and freeze-out geometry of heavy-ion collisions in the few-GeV energy regime

Resolving the RpA​ and v2​ puzzle of D0 mesons in p−Pb collisions at the LHC

Scales in light-nuclei production near the QCD critical point

Affiliations

Resolving the $R_{pA}$ and $v_{2}$ puzzle of $D^{0}$ mesons in $p -$ Pb collisions at the LHC